how set doubleSided: true?

[wuvalue]

my 3dtiles file is single side, i want set doubleSide, how i do ? thanks

[javagl]

This is related to #65 , insofar that this also is just one way in which the materials from glTF should be modified for the whole tileset.

Does your tileset contain B3DM or GLB tile content? I can quickly create a snippet that shows how this can be done.

[wuvalue]

这与#65相关，因为这也只是为整个图块集修改 glTF 材质的一种方式。

您的图块集是否包含 B3DM 或 GLB 图块内容？我可以快速创建一个代码片段来展示如何做到这一点。

yes，b3dm

[javagl]

I updated the snippet that I already posted in the forum at https://community.cesium.com/t/3d-tiles-get-very-dark-textures/26323/17 to modify the materials by making them doubleSided: true:

//
// NOTE: None of the functionality that is shown here is part of the
// public API of the 3D Tiles tools. The functions that are shown here
// use an INTERNAL API that may change at any point in time.
//
import { TileContentProcessing } from "./src/tools/tilesetProcessing/TileContentProcessing";
import { GltfTransform } from "./src/tools/contentProcessing/GltfTransform";
import { TileFormats } from "./src/tilesets/tileFormats/TileFormats";
import { ContentDataTypes } from "./src/base/contentTypes/ContentDataTypes";

// Read a glTF-Transform document from the given input GLB buffer,
// set the materials to be double sided, and return
// a new buffer that was created from the modified document
async function modifyMaterialsInGlb(inputGlb: Buffer) {
  const io = await GltfTransform.getIO();
  const document = await io.readBinary(inputGlb);
  const root = document.getRoot();
  const materials = root.listMaterials();
  for (const material of materials) {
    material.setDoubleSided(true)
  }
  const outputGlb = await io.writeBinary(document);
  return outputGlb;
}

// Read the tile data from the given input B3DM buffer,
// extract the payload (GLB data), modify it by calling
// `modifyMaterialsInGlb`, and create a new B3DM buffer
// with the modified GLB data
async function modifyMaterialsInB3dm(inputB3dm: Buffer) {
  const inputTileData = TileFormats.readTileData(inputB3dm);
  const inputGlb = inputTileData.payload;
  const outputGlb = await modifyMaterialsInGlb(inputGlb);
  const outputTileData = TileFormats.createB3dmTileDataFromGlb(
    Buffer.from(outputGlb),
    inputTileData.featureTable.json,
    inputTileData.featureTable.binary,
    inputTileData.batchTable.json,
    inputTileData.batchTable.binary
  );
  const outputB3dm = TileFormats.createTileDataBuffer(outputTileData);
  return outputB3dm;
}

async function runConversion() {
  const tilesetSourceName = "./data/input/tileset.json";
  const tilesetTargetName = "./data/output/tileset.json";
  const overwrite = true;

  // Create a `TileContentProcessor` that calls modifyMaterialsInB3dm
  // for all B3DM files
  const tileContentProcessor = async (
    content: Buffer,
    type: string | undefined
  ) => {
    if (type !== ContentDataTypes.CONTENT_TYPE_B3DM) {
      return content;
    }
    // A pragmatic try-catch block for the actual modification.
    // In a real application, different error handling could
    // be used.
    console.log("Modifying materials...");
    try {
      const modifiedB3dm = await modifyMaterialsInB3dm(content);
      console.log("Modifying materials... DONE");
      return modifiedB3dm;
    } catch (e) {
      console.log(`ERROR: ${e}`);
      return content;
    }
  };
  // Process the tileset source, and write it to the tileset target,
  // applying the `TileContentProcessor` to all tile contents
  await TileContentProcessing.process(
    tilesetSourceName,
    tilesetTargetName,
    overwrite,
    tileContentProcessor
  );
}

runConversion();

(I have not yet tested this extensively, but if anything doesn't work as expected, just drop me a note)